Many-body interaction effects on the low-kstructure of liquid Kr

Abstract

Neutron diffraction measurements and theoretical calculations of the structure factor S(k) of liquid Kr are extended to small k values (k<4 nm(-1)). The results show that many-body interaction contributions have an increasing effect on S(k) as k-->0, reaching at least 40% of the measured intensity. Both the phase diagram and the low-k structural data of dense Kr turn out to be closely reproduced by the hierarchical reference theory if additional many-body forces are taken into account by an augmented strength of the Axilrod-Teller triple-dipole potential. The experimental density derivative of S(k) is also used for a very sensitive test of the theories and interaction models considered here.

Collective dynamics and molecular interactions in liquidCO2by inelastic neutron scattering and computer simulations

“…Besides water, 7-9 few other simple polyatomic liquids have attracted experimental attention: methanol, 10,11 sulfur dioxide, 12 carbon tetrachloride, 13 and more recently hydrogen and deuterium fluoride. 14,15 The role played by neutron scattering in investigations of the intermolecular potential of fluids is witnessed by studies of static [16][17][18][19][20][21][22][23][24] and dynamic [25][26][27][28] properties of monatomic liquids and gases. Neutron diffraction was proven effective also on the simplest molecular fluids.…”

Effects of three-body interactions on the structure and thermodynamics of liquid krypton

“…We compare the MD curves to the recent small-angle scattering data of Guarini et al 8 along the T = 199 K and Fig. 2 (a) and (b), respectively.…”

“…The same observation can be drawn along the T = 169 K isotherm, as shown in Fig 2 (b), and in this case a very good agreement with the experimental curves is seen when the ddd potential is taken into account. Interesting enough, both experimental data sets of Guarini et al 8 and Barocchi et al 30 , which connect to each other very well around 4 nm −1 , lie between the curves corresponding to ν = ν ddd and ν = ν ef f , for k values in the range between 2.5 and 6.5 nm −1 .…”

“…Such an effective three-body potential was recently used to study the liquid-vapor phase equilibria of argon 21 as well as the small-k part of the static structure factor of krypton in the dense liquid 8 . For instance, to interpret correctly their experimental data, Guarini et al 8 In order to extract a meaningful structure factor S(k) from the MD simulations, the pair correlation g(r) is the key quantity that has to be calculated as precisely as possible.…”

“…As three-body forces are involved, this represents a huge amount of computer time, and we have used a parallel algorithm described in some details in a previous work 29 by Guarini et al 8 and by Barocchi et al 30 , respectively at low-and large-k. These states correspond to temperature T = 199 K and densities n = 12.10, 11.66 and 11.31 nm −3 , T = 169 K with n = 14.57 and 14.22 nm −3 , and T = 130 K with n = 16.83 nm −3 .…”